Manassas is a conservative Virginia city with 36K population and 24K eligible to vote. Today's WashPost gave actual numbers for the primary -- about 5000 total voting with about 3500 voting Democratic (57% Obama, 42% Clinton) and about 1500 voting Republican (50% McCain, 38% Huckabee, 5% Paul).
Virginia allows anybody to vote in any primary, but only one primary, so my guess is that some Republicans voted for Obama, thinking he's less likely to win against McCain. Our city has no Democratic elected officials, but we do have one Independent.
All three locales in the Chesapeake Primary -- VA, MD, DC -- went for Obama and McCain and with the Democrats, VA and MD were about 2 Obama to 1 Clinton with DC about 3 Obama to 1 Clinton. For the Republicans, McCain and Huckabee were much closer in VA and MD, but McCain took 67% in DC (which only has about 5K Republicans).